Thermodynamic engine with a quantum degenerate working fluid

TL;DR

This paper demonstrates that a quantum degenerate Bose-condensed gas can be used as a working fluid in a thermodynamic engine, achieving higher efficiency and power than classical gases, with experimental validation and theoretical support.

Contribution

First experimental realization of a quantum degenerate Bose gas as a working fluid in a thermodynamic engine, showing enhanced performance over non-degenerate gases.

Findings

Significant efficiency and power enhancement with Bose-condensed fluid

Reversibility of the quantum thermodynamic cycle demonstrated

Results match theoretical simulations closely

Abstract

Can quantum mechanical thermodynamic engines outperform their classical counterparts? To address one aspect of this question, we experimentally realize and characterize an isentropic thermodynamic engine that uses a Bose-condensed working fluid. In this engine, an interacting quantum degenerate gas of bosonic lithium is subjected to trap compression and relaxation strokes interleaved with strokes strengthening and weakening interparticle interactions. We observe a significant enhancement in efficiency and power when using a Bose-condensed working fluid, compared to the case of a non-degenerate thermal gas. We demonstrate reversibility, and measure power and efficiency as a function of engine parameters including compression ratio and cycle time. Results agree quantitatively with interacting finite temperature field-theoretic simulations that closely replicate the length and energy scales of the working fluid.